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Suppose $\frac{1}{2} + \frac{1}{3} + \ldots +\frac{1}{x} > 1\frac{1}{2}$. What is the smallest possible value for $x$?

 May 25, 2015

Best Answer 

 #1
avatar+129852 
+10

1/2 + 1/3 +......+ 1/x  > 3/2

 

5/6 + 1/4 + 1/5 +.......+ 1/x > 3/2

 

1/4 + 1/5 +......+ 1/x > 2/3

 

9/20 + 1/6 + 1/7 > 2/3

 

1/6 + 1/7 > 13/60

 

1/7 > 1/20

 

So.....7 is the smallest integer

 

 

 May 25, 2015
 #1
avatar+129852 
+10
Best Answer

1/2 + 1/3 +......+ 1/x  > 3/2

 

5/6 + 1/4 + 1/5 +.......+ 1/x > 3/2

 

1/4 + 1/5 +......+ 1/x > 2/3

 

9/20 + 1/6 + 1/7 > 2/3

 

1/6 + 1/7 > 13/60

 

1/7 > 1/20

 

So.....7 is the smallest integer

 

 

CPhill May 25, 2015

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